The disclosure concerns a printing method and a printing apparatus.
Digital printing apparatuses are in the position to individually print items of information line by line and in particular pixel by pixel. For example, such printing apparatuses are based on electrographic, magnetographic or inkjet techniques. The printing apparatuses are thereby normally designed either to print to sheet-shaped recording media or to print to web-shaped recording media.
US 2007/0172270 A1 shows what is known as a single page printing system to print to sheet-shaped recording media. The individual sheets are thereby drawn from a sheet stock; selectively supplied to one of two printing stations; printed there; the print image is subsequently fixed on the respective sheet; and the sheet is subsequently supplied to an output unit.
In the printing of single sheets, the requirement exists (otherwise than in the printing of web-shaped recording media) to position the print image on the respective single sheet in register with the respective edges of the sheet that are situated transverse to the paper travel direction or the printing direction. For this, upon transport of the individual sheets in the printing apparatus it is necessary to ensure that the individual sheets arrive at the respective printing stations at predetermined points in time. In order to compensate for speed fluctuations and avoid that two sheets collide or even overlap during the transport, a certain interval (what is known as a “gap”) is normally provided in the transport of sheets in the single page printing apparatuses.
A method and a system with which sheet gaps in the single page printing system can be calculated and monitored is described in U.S. Pat. No. 7,804,621 B2.
In the German Patent Application Nr. 10 2011 000 220.0 (not published prior to this Application), a digital printing system is described in which the printing process is controlled so that an in-register [positionally accurate] printing on the recording medium is possible when the recording medium is transported past a print head at variable speed.
In the German Patent Application Nr. 10 2010 037 303.6 by the applicant, a method is described for per-point activation of a print head in which pixel data are sorted in a data sorting memory and then are read out line by line to control the print head.
In the German Patent Application Nr. 10 2010 037 854.2 by the applicant, a method is described for controlling a printing process in an inkjet printing apparatus in which a line clock is generated for printing a print line, and individual print heads are individually activated with an offset relative to the line clock to eject printing ink.
The previously described publications and Patent Applications or, respectively, Patent Applications corresponding with these in other countries, are herewith incorporated by reference into the present Specification.